This connector seems broken to me, as the plastic locking part has separated from the body of the connector. I couldn't figure out the orientation of the locking part until I started this message. Now I think I have. It has clicked in nicely. I'm worried that it isn't very secure because of the broken bit, so have used a bit of sticky tape to hold the cable to the board.

Now I have found the same problem on another connector. Same solution. This laptop has suffered at the hands of a previous attempt at repair by the looks. The power socket, which was loose in the body of the laptop, has loose wires, bad soldering, with broken location lugs in the body. A good old bit of Aussie "bush mechanics" is all I can do. Here's hoping.